Make the cinnamon swirl filling: In a small bowl, stir together the melted butter, brown sugar, and ground cinnamon until completely combined into a smooth paste. Transfer the mixture into a pastry piping bag or a heavy-duty ziplock bag and set aside to cool slightly at room temperature (it will thicken into the perfect pipeable consistency).
Whisk the cream cheese glaze: In a medium mixing bowl, beat the softened cream cheese and softened butter with an electric hand mixer or whisk until smooth and creamy. Gradually beat in powdered sugar and vanilla extract. Slowly add whole milk, 1 tablespoon at a time, until the glaze reaches a smooth, luscious, pourable consistency. Set aside.
Mix the pancake batter: In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt. In a separate bowl, whisk together the buttermilk, eggs, melted butter, and vanilla extract. Pour the wet ingredients into the dry ingredients and gently fold with a rubber spatula just until combined. (Do not overmix; small lumps should remain for the fluffiest texture). Let the batter rest for 5 minutes.
Griddle & pipe the swirl: Heat a large non-stick griddle or cast-iron skillet over medium-low heat and lightly brush with melted butter. Pour 1/3 cup of pancake batter onto the griddle for each pancake. Snip a small corner off the ziplock or piping bag. Working quickly, pipe a spiral swirl of the cinnamon mixture starting from the center and spiraling outward toward the edges of each pancake.
Cook & gently flip: Cook for 2 to 3 minutes until bubbles burst on the pancake surface and the edges look set. Gently slide a wide spatula underneath and carefully flip the pancake. Cook for an additional 1 to 2 minutes on the swirl side until golden. (The cinnamon brown sugar will caramelize into a shiny, gooey crust—keep the heat medium-low so it doesn't burn). Wipe the griddle surface clean with a damp paper towel between batches.
Stack, glaze & serve: Stack warm pancakes high on serving plates. Drizzle generously with warm cream cheese glaze, top with a pat of butter, and finish with a dusting of cinnamon. Serve immediately with warm maple syrup!